Abstract:

An adapter (21) for tapping used in a turret punch press, comprises: a
ring gear (29) in which a tapping tool (25) is mountable; and a gear
holder (31) in which the ring gear is disposed and which is mountable on
a turret (9) of the turret pinch press so as to locate the disposed ring
gear (29) at a position corresponding to a punch mounting section (33)
formed in advance in the turret (9) of the turret punch press.

Claims:

1. An adapter for tapping used in a turret punch press, comprising: a
ring gear in which a tapping tool is mountable; and a gear holder in
which the ring gear is disposed and which is mountable on a turret of the
turret pinch press so as to locate the disposed ring gear at a position
corresponding to a punch mounting section formed in advance in the turret
of the turret punch press.

2. The adapter for tapping according to claim 1, wherein at least two
ring gears are disposed, each of which is equivalent to the ring gear,
tooth portions of the ring gears are separated from each other in an
extending direction of central axes of rotation of the respective ring
gears, part of the tooth portion of one ring gear out of the ring gears
overlap part of the tooth portion of another one ring gear out of the
ring gears when viewed in the extending direction of the central axes of
rotation of the ring gears, and the gear holder is provided with an
intermediate gear meshed with the ring gears.

3. A tapping tool mountable on an adapter for tapping including: ring
gear in which the tapping tool is mountable; and a gear holder in which
the ring gear is disposed and which is mountable on a turret of the
turret punch press so as to locate the disposed ring gear at a position
corresponding to a punch mounting section formed in advance in the
turret, the tapping tool comprising: a cylindrical body including a
master screw formed on an inner circumference thereof and being disposed
in a through-hole of the ring gear and a mounting section of the turret;
and a rotating body being configured to be capable of holding a tap,
including a master screw formed on an outer circumference thereof so as
to be threadedly engaged with the master screw on the cylindrical body,
being disposed inside the cylindrical body by threadedly engaging the
master screw with the master screw on the cylindrical body, rotating
along with rotation of the ring gear, and moving in an extending
direction of a central axis of the rotation.

4. The tapping tool according to claim 3, further comprising: rotation
regulator to regulate rotation of the rotating body relative to the
cylindrical body when the tapping tool is detached from the turret.

5. The tapping tool according to claim 3, wherein the rotating body is
configured to be electrically insulated from the adapter for tapping and
the turret when the tapping tool is disposed in the through-hole of the
ring gear and the mounting section of the turret.

6. The tapping tool according to claim 4, wherein the rotating body is
configured to be electrically insulated from the adapter for tapping and
the turret when the tapping tool is disposed in the through-hole of the
ring gear and the mounting section of the turret.

7. A tap die used in cooperation with a tap tool to be mounted on and
used in a punch press, comprising: a cylindrical die body; and an inner
cylinder being provided inside the die body and including a tap contact
member pressed downward by a tap provided vertically movably to the tap
tool, the inner cylinder being provided vertically movably and biased
upward, wherein an upper end of the inner cylinder is provided
substantially at a same height as an upper end of the die body, the tap
contact member is formed of a plate material, and the tap contact member
is so formed that a width dimension of the tap contact member in a
vertical direction is greater than a plate thickness dimension thereof.

8. The tap die according to claim 7, wherein an upper surface of the tap
contact member is provided at a position lower than the upper end of the
inner cylinder, and a lower end of the tap contact member is provided at
a position higher than an air ejection port provided to the inner
cylinder.

9. The tap die according to claim 7, wherein an upper surface of the tap
contact member is formed into a curved surface whose both ends in a
thickness direction of the tap contact member are made lower.

10. The tap die according to claim 8, wherein the upper surface of the
tap contact member is formed into a curved surface whose both ends in a
thickness direction of the tap contact member are made lower.

11. A method of detecting overstroke of a tap mounted on a tap tool to be
mounted on and used in a punch press, the method comprising the steps of:
providing an inner cylinder including a tap contact member pressed
downward by a tap provided vertically movably to the tap tool, the inner
cylinder being provided vertically movably and biased upward inside a
cylindrical die body of a tap die to be used in cooperation with the tap
tool; providing a plurality of upper and lower communicating portions in
an outer circumferential surface of the inner cylinder, the communicating
portions each being communicatively connectable to and disconnectable
from an air supply port provided to the die body; providing a fluid
sensor to detect states of communicative connection and disconnection
between the air supply port and the communication portions, in a
connecting path connecting an air source to the air supply port; and
detecting overstroke of the tap when the fluid sensor performs ON, OFF,
and ON operations at the time of a descending action of the tap provided
to the tap tool.

12. A tap die used in cooperation with a tap tool to be mounted on and
used in a punch press, comprising: a cylindrical die body; and an inner
cylinder being provided inside the cylindrical die body and including a
tap contact member pressed downward by a tap provided vertically movably
to the tap tool, the inner cylinder being provided vertically movably and
biased upward inside the cylindrical die body; an air supply port
provided to the die body; and a plurality of upper and lower
communicating portions provided in an outer circumferential surface of
the inner cylinder, and being communicatively connectable to and
disconnectable from the air supply port.

13. The tap die according to claim 12, wherein the plurality of upper and
lower communicating portions are provided respectively to portions
located at one side of a concave portion formed in the outer
circumferential surface of the inner cylinder.

Description:

TECHNICAL FIELD

[0001] The present invention relates to a tapping machine, a die, and a
method of detecting overstroke of a tap, and specifically to: an adapter
for tapping disposed and used in a turret punch press; a tapping tool; a
tap die capable of improving a discharge performance of chips generated
at the time of tapping; a method of detecting overstroke of a tap when
the tap's stroke reaches or exceeds a predetermined stroke length; and a
tap die used for the method.

BACKGROUND ART

[0002] A conventional turret punch press performs punching and press
working by using punches and dies.

[0003] In the meantime, due to increasing diversity and complexity in the
shapes of workpieces in recent years, there is a growing demand for
performing not only various types of punching but also various types of
tapping on works by use of a single turret punch press.

[0004] The above-mentioned technique has been disclosed in Patent Document
1 and Patent Document 2, for example.

[0005] Incidentally, in a conventional turret punch press, mounting
sections (mounting sections for tools) provided to a turret are designed
as mounting sections dedicated for punches or mounting sections dedicated
for tapping tools, and the punching tools and the tapping tools are
mounted on the mounting sections of the respective types. Accordingly,
the mounting section for tapping tool is used exclusively for the tapping
tools and it is therefore not possible to mount any punching tools on the
mounting section for tapping tool even in the case of a process using no
tapping tools. Accordingly, there is a problem of a decrease in the types
of tools to be loaded on the turret, which leads to a difficulty in
handling various processes with a single turret punch press.

[0006] Meanwhile, to be specific, tapping on a plate-shaped workpiece may
be performed by subjecting the workpiece to punching to form pilot holes
having small diameters in the workpiece and then performing tapping
either directly on the pilot holes or after subjecting the pilot holes to
burring. Therefore, a punch press includes: a tap tool with a tap
provided thereto rotatably and vertically movably for performing tapping.
A tap die used in cooperation with the tap tool is given at a position
below this tapping tool.

[0007] The above-mentioned technique has been disclosed in Patent Document
3, for example.

[0008] A tap die disclosed in Patent Document 3 has a configuration as
shown in FIG. 1. Specifically, a tap die 505 to be used in cooperation
with a tap tool 503, which is used by being mounted on a punch holder 501
such as an upper turret in a turret punch press, is detachably
replaceably provided in a die holder 507 such as a lower turret in the
punch press. The tap die 505 includes a cylindrical die body 509. An
inner cylinder 515 is provided vertically movably inside this die body
509. The inner cylinder 515 has a tap contact member 513 located on an
upper part thereof and pressed downward by a tap 511 being rotatably and
vertically movably provided to the tap tool 103.

[0009] The inner cylinder 515 is always biased upward by means of coil
springs 517, whereby an upper surface of this inner cylinder 515 is in
contact with a lower surface of an inner flange 509F provided on an upper
part of the die body 509. Further, a circumferential groove 521 capable
of being communicatively connected to and disconnected from an air supply
port 519 provided in the die body 509 is formed in an outer
circumferential surface of the inner cylinder 515. This circumferential
groove 521 communicates with the inside of the inner cylinder 515.

[0010] The air supply port 519 in the die body 509 is connected to an air
source 523 via a connecting path 525. A pressure switch 527 for detecting
whether the air supply port 519 and the circumferential groove 521 are in
a communicatively connected state or disconnected state is connected to
this connecting path 525.

[0011] Therefore, tapping is performed on a pilot hole WH in a workpiece W
by: positioning the pilot hole WH formed in the workpiece W on the die
body 509 in the tap die 505; bringing the tap tool 503 downward by use of
a ram (a striker) vertically movably provided to the punch press;
pressing and fixing the workpiece W onto the die body 509; bringing the
tap 511 relatively downward; and rotating the tap 511.

[0012] Thereafter, as a lower end (a tip end) of the tap 511 comes into
contact with the tap contact member 513 and lowers the inner cylinder 515
against a biasing force of the coil springs 517, the air supply port 519
is connected to the circumferential groove 521. Therefore, an air
pressure inside the connecting path 525 is changed from a high pressure
to a low pressure as the air supply port 519 previously in the
communicatively disconnected state is connected to the circumferential
groove 521, and it is hence possible to detect this change in air
pressure by use of the pressure switch 527. Accordingly, when the tap 511
moves up after descending from a lifted position to the lowest descending
position, it is possible to detect fracture and the like of the tap 511,
for example, by detecting whether or not the pressure switch 527 repeats
ON-OFF-ON operations.

[0013] However, in the above-described configuration, when a tap tool
provided with a tap having a large diameter is erroneously mounted as the
tap tool 503 to be mounted on the punch holder 501 in the punch press
instead of the tap tool 503 provided with the tap 511 having the small
diameter, a stroke length of the tap having the large diameter and a
large screw pitch becomes greater even when the number of revolutions of
the tap is the same. Accordingly, the tap is apt to lower the inner
cylinder 515 after the inner cylinder 515 reaches a descending end, for
example. This leads to a problem of causing fracture of the tap, damage
on the tap tool, or the like.

[0014] Meanwhile, the above-described conventional configuration also has
a problem that long chips being generated at the time of tapping may
twine around the tap contact member, a problem that part of chips may
enter a gap between the upper surface of the inner cylinder 515 and the
inner flange 509F of the die body 509, and some other problems.

[0018] The present invention has been made to solve the above-mentioned
problems. Therefore, a first object thereof is to provide an adapter for
tapping which can easily handle various processes by use of a single
turret punch press, and to provide a tapping tool used for this adapter
for tapping.

[0019] A second object of the present invention is to provide a tap die
which is capable of preventing chips from twining around a tap contact
member of the tap die and of preventing chips from entering a gap between
a die body and an inner cylinder of the tap die.

[0020] Further, a third object of the present invention is to provide a
method of detecting tap overstroke to avoid fracture of a tap mounted on
a tap tool and damage on the tap tool by detecting overstroke of the tap,
and to provide a tap die used for the method.

Technical Solution

[0021] A first aspect of the present invention to achieve the
above-described first object is an adapter for tapping used in a turret
punch press, comprising: a ring gear in which a tapping tool is
mountable; and a gear holder in which the ring gear is disposed and which
is mountable on a turret of the turret pinch press so as to locate the
disposed ring gear at a position corresponding to a punch mounting
section formed in advance in the turret of the turret punch press.

[0022] A second aspect of the present invention dependent on the first
aspect is the adapter for tapping wherein, at least two ring gears are
disposed, each of which is equivalent to the ring gear; tooth portions of
the ring gears are separated from each other in an extending direction of
central axes of rotation of the respective ring gears; part of the tooth
portion of one ring gear out of the ring gears overlap part of the tooth
portion of another one ring gear out of the ring gears when viewed in the
extending direction of the central axes of rotation of the ring gears;
and the gear holder is provided with an intermediate gear meshed with the
ring gears.

[0023] A third aspect of the present invention is a tapping tool mountable
on an adapter for tapping including: ring gear in which the tapping tool
is mountable; and a gear holder in which the ring gear is disposed and
which is mountable on a turret of the turret punch press so as to locate
the disposed ring gear at a position corresponding to a punch mounting
section formed in advance in the turret, the tapping tool comprising: a
cylindrical body including a master screw formed on an inner
circumference thereof and being disposed in a through-hole of the ring
gear and a mounting section of the turret; and a rotating body being
configured to be capable of holding a tap, including a master screw
formed on an outer circumference thereof so as to be threadedly engaged
with the master screw on the cylindrical body, being disposed inside the
cylindrical body by threadedly engaging the master screw with the master
screw on the cylindrical body, rotating along with rotation of the ring
gear, and moving in an extending direction of a central axis of the
rotation.

[0024] A fourth aspect of the present invention dependent on the third
aspect is the tapping tool further comprising: rotation regulating means
(rotation regulator) for regulating rotation of the rotating body
relative to the cylindrical body when the tapping tool is detached from
the turret.

[0025] A fifth aspect of the present invention dependent on any one of the
third and fourth aspects is the tapping tool wherein the rotating body is
configured to be electrically insulated from the adapter for tapping and
the turret when the tapping tool is disposed in the through-hole of the
ring gear and the mounting section of the turret.

[0026] A sixth aspect of the present invention to achieve the
above-described second object is a tap die used in cooperation with a tap
tool to be mounted on and used in a punch press, comprising: a
cylindrical die body; and an inner cylinder being provided inside the die
body and including a tap contact member pressed downward by a tap
provided vertically movably to the tap tool, the inner cylinder being
provided vertically movably and biased upward, wherein an upper end of
the inner cylinder is provided substantially at a same height as an upper
end of the die body; the tap contact member is formed of a plate
material; and the tap contact member is so formed that a width dimension
of the tap contact member in a vertical direction is greater than a plate
thickness dimension thereof.

[0027] A seventh aspect of the present invention dependent on the sixth
aspect is the tap die wherein an upper surface of the tap contact member
is provided at a position lower than the upper end of the inner cylinder;
and a lower end of the tap contact member is provided at a position
higher than an air ejection port provided to the inner cylinder.

[0028] An eighth aspect of the present invention dependent on any one of
the sixth and seventh aspects is the tap die wherein the upper surface of
the tap contact member is formed into a curved surface whose both ends in
a thickness direction of the tap contact member are made lower.

[0029] A ninth aspect of the present invention to achieve the
above-described third object is a method of detecting overstroke of a tap
mounted on a tap tool to be mounted on and used in a punch press, the
method comprising the steps of providing an inner cylinder including a
tap contact member pressed downward by a tap provided vertically movably
to the tap tool, the inner cylinder being provided vertically movably and
biased upward inside a cylindrical die body of a tap die to be used in
cooperation with the tap tool; providing a plurality of upper and lower
communicating portions in an outer circumferential surface of the inner
cylinder, the communicating portions each being communicatively
connectable to and disconnectable from an air supply port provided to the
die body; providing a fluid sensor to detect states of communicative
connection and disconnection between the air supply port and the
communication portions, in a connecting path connecting an air source to
the air supply port; and detecting overstroke of the tap when the fluid
sensor performs ON, OFF, and ON operations at the time of a descending
action of the tap provided to the tap tool.

[0030] A tenth aspect of the present invention is a tap die used in
cooperation with a tap tool to be mounted on and used in a punch press,
comprising: a cylindrical die body; and an inner cylinder being provided
inside the cylindrical die body and including a tap contact member
pressed downward by a tap provided vertically movably to the tap tool,
the inner cylinder being provided vertically movably and biased upward
inside the cylindrical die body; an air supply port provided to the die
body; and a plurality of upper and lower communicating portions provided
in an outer circumferential surface of the inner cylinder, and being
communicatively connectable to and disconnectable from the air supply
port.

[0031] An eleventh aspect of the present invention dependent on the tenth
aspect is the tap die wherein the plurality of upper and lower
communicating portions are provided respectively to portions located at
one side of a concave portion formed in the outer circumferential surface
of the inner cylinder.

Advantageous Effects

[0032] According to the present invention described in the aforementioned
first to the fifth aspects, it is possible to achieve an effect of
allowing easy handling of various processes by use of a single turret
punch press.

[0033] In addition, according to the present invention described in the
aforementioned sixth to eighth aspects, it is possible to prevent chips
from twining around the tap contact member and to prevent chips from
entering a gap between the die body and the inner cylinder. Therefore, it
is possible to solve the above-described problem of the related art.

[0034] Further, according to the present invention described in the ninth
to eleventh aspects, the fluid sensor carries out ON-OFF-ON operations
when the tap provided to the tap tool descends and hence, it is possible
to detect overstroke of the tap mounted on the tap tool. Therefore, it is
possible to solve the above-described problem of the related art.

[0036]FIG. 2 is a view showing a schematic configuration of a turret
punch press 1.

[0037]FIG. 3 is a perspective view showing a state of disposing, on an
upper turret 9, an adapter 21 for tapping, and an adapter 23 for
tapping-unit rotational drive constituting tapping-unit rotationally
driving means.

[0038]FIG. 4 is a perspective view showing a schematic configuration of
the adapter 23 for tapping unit rotary drive in a see-through manner.

[0039]FIG. 5 is a perspective view showing the schematic configuration of
the adapter 23 for tapping unit rotary drive (a perspective view which is
viewed from a different angle from FIG. 4).

[0040]FIG. 6 is a perspective view showing a schematic configuration of
the adapter 21 for tapping in a see-through manner.

[0041]FIG. 7 is a perspective view of a die 27 and of a tapping tool 25
to be disposed on the adapter 21 for tapping.

[0042] FIG. 8 is a cross-sectional view showing a schematic configuration
of the tapping tool 25.

[0055] A mode for carrying out the present invention will be described
below by using drawings.

[0056]FIG. 2 is a view showing a schematic configuration of a turret
punch press 1, on which an adapter for tapping, a tapping tool, a tap
die, and the like based on the present invention are mounted and which
embodies a method of detecting overstroke of a tap, the tap die being
capable of improving a discharge performance of chips generated at the
time of tapping.

[0057] The turret punch press 1 includes a frame 3. Moreover, the turret
punch press 1 includes: a table 5 supporting a plate-shaped workpiece W;
a workpiece positioning device 7 used for positioning of the workpiece W;
and a turret device 13 including a disc-shaped upper turret 9 on which
multiple punches (not shown) or tapping units (tapping tools) can be
disposed (an upper turret capable of being positioned pivotally around a
central axis of rotation CL1), and a disc-shaped lower turret 11 on which
multiple dies (not shown) or holed dies can be freely disposed in lower
positions corresponding to the punches or the tapping units.

[0058] Moreover, a striker 15 striking (applying a force in a downward
direction to) the tapping units or the punches in the upper turret 9, and
a ram body 17 are provided vertically movably to the frame 3. In order to
selectively strike the punches or the tapping units arranged in a radial
direction of the upper turret 9, a striker moving mechanism 19 is
provided between the striker 15 and the ram body 17.

[0059] Further, tapping-unit rotationally driving means (not shown in FIG.
2) for rotationally driving the tapping units is provided on an upper
part of the frame 3.

[0060] Subsequently, an adapter 21 for tapping, and the like will be
described.

[0061] The adapter 21 for tapping is disposed and used on an upper surface
of the upper turret 9 of the turret punch press 1 and includes ring gears
29 and a gear holder 31.

[0062] The ring gears 29 are so configured that tapping tools 25 can be
mounted on (detachably attached to) the inside thereof. The gear holder
31 is so configured that the upper turret 9 can be mounted thereon
(detachably attached thereto). In a state where the gear holder 31 is
mounted on the upper turret 9, the ring gears 29 disposed in the gear
holder 31 are located in positions corresponding to punch mounting
sections 33 formed in advance in the upper turret 9 of the turret punch
press 1.

[0063] At least two ring gears 29 (a plurality: four pieces in FIG. 6 and
FIG. 10) are disposed in one gear holder 31. Tooth portions of the ring
gears 29 are located away from one another in an extending direction of
central axes of rotation CL2 of the respective ring gears 29 (see FIG.
11). On the other hand, when viewed in the extending direction of the
central axes of rotation CL2 of the ring gears 29, a portion on a tip end
side of the tooth portions of one ring gear 29 (e.g., a ring gear 29A)
out of two ring gears 29 overlaps with a portion on a tip end side of the
tooth portion of the other ring gear 29 (e.g., a ring gear 29D) out of
the two ring gears 29 (see FIG. 10). The gear holder 31 is provided with
an intermediate gear 35 which is engaged with the ring gears 29.

[0064] Each tapping tool 25 is configured mountable on the adapter 21 for
tapping as described above and is provided with a cylindrical body 37 and
a rotating body 39 (see FIG. 8).

[0065] A master screw (a female screw) 41 is formed on an inner
circumference of the cylindrical body 37. The cylindrical body 37 is
inserted to and disposed in a through-hole of the ring gear 29 and the
mounting section 33 of the upper turret 9 in such a state that rotation
of the cylindrical body 37 may be regulated, when the adapter 21 for
tapping is disposed on the upper turret 9.

[0066] The rotating body 39 includes a tap holding mechanism, and is so
configured that a tap 43 can be mounted thereon (detachably attached
thereto). A master screw (a male screw) 45 threadedly engaged with the
master screw 41 on the cylindrical body 37 is formed on an outer
circumference of the rotating body 39. The rotating body 39 is located
inside the cylindrical body 37 as this master screw 45 is threadedly
engaged with the master screw 41. Meanwhile, when the rotating body 39 is
rotated by rotation of the ring gear 29 in a state where the adapter 21
for tapping is disposed on the upper turret 9 and the tapping tool 25
(the cylindrical body 37) is disposed in the through-hole of the ring
gear 29 and the mounting section 33 of the upper turret 9, the rotating
body 39 (the tap 43) moves in the extending direction of the central axis
of rotation CL2 thereof (to move by way of the threaded engagement
between the master screws 41 and 45).

[0067] The tapping tool 25 is provided with rotation regulating means
(rotation regulator) 47. The rotation regulating means 47 regulates
rotation of the rotating body 39 relative to the cylindrical body 37 when
the tapping tool 25 is detached from the upper turret 9 and the adapter
21 for tapping (the adapter for tapping disposed on the upper turret 9).
Here, the rotation regulating means 47 is configured to be inactivated so
as to allow the rotating body 39 to rotate relative to the cylindrical
body 37, when the tapping tool 25 is disposed in the through-hole of the
ring gear 29 and the mounting section 33 of the upper turret 9 in a state
where the adapter 21 for tapping is disposed on the upper turret 9.

[0068] Meanwhile, in the tapping tool 25, when the adapter 21 for tapping
is disposed on the upper turret 9 and the tapping tool 25 is disposed in
the through-hole of the ring gear 29 and the mounting section 33 of the
upper turret 9, the rotating body 39 and the tap 43 disposed in this
rotating body 39 are configured to be electrically insulated from the
adapter 21 for tapping and the upper turret 9.

[0069] The tapping tool 25 and so forth will be described further in
detail.

[0070] Each ring gear 29 is formed into a cylindrical shape and provided
with a columnar through-hole at a central part thereof to mount the
tapping tool 25, and teeth of a spur gear, for example, are formed on an
outer circumference thereof.

[0071] The upper turret 9 is formed into a disc shape. Each punch mounting
section 33 of the upper turret 9 includes a through-hole of a columnar
shape, for example, which penetrates the upper turret 9 in a thickness
direction thereof.

[0072] When the gear holder 31 with the ring gears 29 disposed therein is
mounted on the upper turret 9, the central axes of rotation CL2 of the
ring gears 29 extend in the thickness direction of the upper turret 9 and
the through-holes of the mounting sections 33 of the upper turret 9 and
the through-holes of the ring gears 29 substantially overlap one another
when viewed in the thickness direction of the upper turret 9. Moreover,
the central axes of the through-holes of the upper turret 9 and the
central axes of rotation CL2 of the through-holes of the ring gears 29
coincide with one another. Further, through-holes 21A provided in the
gear holder 31 supporting the ring gears 29 substantially overlap the
through-holes of the mounting sections 33 of the upper turret 9 and the
through-holes of the ring gears 29 when viewed in the thickness direction
of the upper turret 9 (see FIG. 11).

[0073] The ring gears 29 are located in mutually different attaching
positions on the gear holder 31 but are formed substantially into the
same shape. A facewidth of each of the ring gears 29 is set smaller than
a half value of a height of the gear holder 31 which is in a range from
about 1/3 to 1/5, for example. The number of teeth on the intermediate
gear 35 is fewer than the number of teeth on each ring gear 29, for
example. A facewidth of the intermediate gear 35 is greater than twice of
the facewidth of each ring gear 29 but smaller than the height of the
gear holder 31.

[0074] Moreover, when the ring gears 29 and the intermediate gear 35 are
disposed in the gear holder 31, an upper end of the tooth portion of one
of the ring gears 29 existing on the uppermost side in the vertical
direction (the extending direction of the central axes of rotation CL2 of
the gears 29 and 35) is located at the same position as an upper end of
the tooth portion of the intermediate gear 35, while a lower end of the
tooth portion of another one of the ring gears 29 existing on the
lowermost side is located at the same position as a lower end of the
tooth portion of the intermediate gear 35. In addition, the upper end of
the tooth portion of the intermediate gear 35 is located at a position
lower than an upper end of the gear holder 31 while the lower end of the
tooth portion of the intermediate gear 35 is located at a position higher
than a lower end of the gear holder 31.

[0075] To put it in more detail, the disc-shaped upper turret 9 is
disposed such that the thickness direction thereof may be defined as the
vertical direction, and is capable of freely deciding an index position
pivotally around the central axis of rotation CL1 that extends in the
vertical direction as described previously.

[0076] The multiple columnar through-holes constituting the mounting
sections 33 of the upper turret 9 are formed in the upper turret 9 while
extending in the vertical direction. Moreover, these through-holes are
arranged in a line or in multiple lines along a radial direction of the
upper turret 9 and are provided at predetermined intervals along a
circumferential direction of the upper turret 9. When the adapter 21 for
tapping is not disposed, punches for performing punching, and the like
can be disposed freely in the mounting sections 33.

[0077] Here, as is already understood, the upper turret 9 in this
embodiment is assumed to be disposed so as to align the thickness
direction thereof with the vertical direction, for example. Therefore,
the central axes of rotation CL2 of the through-holes constituting the
mounting sections 33 of the upper turret 9 and the central axes of
rotation CL2 of the ring gears 29 are supposed to extend in the vertical
direction.

[0078] Meanwhile, the adapter 21 for tapping is provided with four ring
gears 29 (29A, 29B, 29C, and 29D), for example, and is used after
integrally disposed on the upper side of the upper turret 9 at positions
where four through-holes (the though holes constituting the mounting
sections 33: the through-holes which are adjacent to one another in the
radial direction of the upper turret 9 and adjacent to one another in the
circumferential direction of the upper turret 9) are provided in the
upper turret 9, in such a manner as to cover the through-holes. Here, the
number of the ring gears 29 and the like may be a plural number other
than four.

[0079] The gear holder 31 includes a lower frame 49 and an upper frame 51.
The ring gears 29 are supported rotatably (so as to be rotatable around
the axes CL2) on the gear holder 31 through bearings 53. Here, in the
state where the gear holder 31 (the adapter 21 for tapping) with the ring
gears 29 disposed therein is integrally disposed on the upper turret 9 by
use of fasteners such as bolts, the central axes of the four
through-holes of the upper turret 9 and the central axes CL2 of the four
ring gears 29 coincide with one another.

[0080] As described previously, each tapping tool 25 includes the
cylindrical body 37 and the rotating body 39. The cylindrical body 37
includes a cylindrical outer holder 55 and a cylindrical gauge nut 57.

[0081] In the state where the tapping tool 25 is disposed in the mounting
section 33 of the upper turret 9 and the adapter 21 for tapping, the
outer holder 55 is biased upward relative to the upper turret 9 by a
lifter spring 59 (see FIG. 11). Meanwhile, in the above state, the outer
holder 55 is prevented from rotating around the axis CL2, as a key 61
provided at a lower part of the through-hole of the upper turret 9 is
engaged with a key groove 63 provided at a lower part of the outer
circumference of the outer holder 55. That is, the outer holder 55 is
movable only in the vertical direction relative to the upper turret 9.

[0082] The gauge nut 57, on which the master screw 41 is fanned, is
provided at an inner side of an intermediate part, in the height
direction, of the outer holder 55. The gauge nut 57 is biased upward
relative to the outer holder 55 by a lifter spring 65. Meanwhile, a key
groove 67 is formed in an outer circumference of the gauge nut 57. The
gauge nut 57 is prevented from rotating around the axis CL2 as this key
groove 67 is engaged with a key 69 provided to the outer holder 55. That
is, the gauge nut 57 is movable only in the vertical direction relative
to the outer holder 55.

[0083] The rotating body 39 includes: a shaft (a ram) 71 which has a lower
side formed into a cylindrical shape and an upper side formed into a
columnar shape; the tap holding mechanism to which the tap 43 is
detachably attached (the tap holding mechanism includes a columnar tap is
holder body 73); a shaft supporter body 75 having a lower side formed
into a cylindrical shape and an upper side formed into a columnar shape;
a lower-side pressing-body supporter body 77 formed into a disc shape; an
upper-side pressing-body supporter body 79 formed into a ring shape; a
pressing body 81 formed into a disc shape; an inner holder 83 formed into
a cylindrical shape; and a driving block 85 formed into a ring shape.
Here, a covering member 74 is formed below the shaft 71 by use of a screw
72 so that the tap 43 can be easily attached and detached to and from
each tap holder body 73.

[0084] The inner holder 83 and the driving block 85 are integrally fixed
to each other. The inner holder 83 and the driving block 85 are rotatably
supported on the outer holder 55 (so as to be rotatable around the axis
CL2) through bearings 87 so as to allow the inner holder 83 to enter the
inside of an upper part of the outer holder 55 and to allow the driving
block 85 to protrude above the outer holder 55.

[0085] A groove 89 is formed in an outer circumference of the driving
block 85 and a release lever 91 is provided in this groove 89 so as to be
turnable around a shaft 93. In the state where the tapping tool 25 is not
disposed on the upper turret 9 or the adapter 21 for tapping, the release
lever 91 is biased by an elastic body such as a compression coil spring
95, whereby a part of the release lever 91 enters a groove 97 formed in
an upper end of the outer holder 55 so as to prevent the inner holder 83
and the driving block 85 from rotating relative to the outer holder 55.
On the other hand, when the tapping tool 25 is disposed on the upper
turret 9 and the adapter 21 for tapping, another part of the release
lever 91 is pressed and turned by inner walls of the gear holder 31 and
the ring gear 29, whereby the aforementioned part of the release lever 91
comes out of the groove 97 formed in the upper end of the outer holder 55
so as to allow the inner holder 83 and the driving block 85 to rotate
relative to the outer holder 55.

[0086] The tap holding mechanism (the tap holder body 73) is provided on a
lower side of the inside of the shaft 71. The tap holder body 73 is
prevented from rotating relative to the shaft 71 as key grooves 99 formed
in an outer circumference of this tap holder body 73 are engaged with
keys 101 provided to the shaft 71, so that the tap holder body 73 can
move only for a predetermined distance in the vertical direction.
Meanwhile, the tap holder body 73 is biased downward by an elastic body
such as a compression coil spring 103. Note that the tap holder body 73
(the tap 43) is located at the lowest position relative to the shaft 71
in the state shown in FIG. 8.

[0087] The shaft 71 is supported, on this lower side, on the outer holder
55 through a bearing 107, and is rotatable relative to the outer holder
55 (rotatable around the axis CL2) and vertically movable relative to the
outer holder 55. Note that the shaft 71 is located at the highest
position relative to the outer holder 55 in the state shown in FIG. 7.

[0088] Meanwhile, a ring-like flange 109 is formed at a lower end of the
shaft 71. A dimension (thickness) in the vertical direction of this
flange 109 is small. A groove (a notch) 111 is formed in the flange 109.
As this groove 111 is engaged with a key (a pin) 113 provided to the
outer holder 55, the shaft 71 is prevented from rotating relative to the
outer holder 55 in the state shown in FIG. 8. Here, when the shaft 71
descends slightly from the state shown in FIG. 8 relative to the outer
holder 55, the groove 111 on the flange 109 is disengaged from the key
113 on the outer holder 55 so that the shaft 71 can rotate relative to
the outer holder 55.

[0089] The master screw 45 is formed on the outer circumference of an
intermediate portion, in the vertical direction, of the shaft 71 and this
master screw 45 is threadedly engaged with the master screw 41 on the
gauge nut 57. Therefore, when the shaft 71 rotates relative to the gauge
nut 57, the shaft 71 (the tap 43) moves in the vertical direction
relative to the gauge nut 57 while rotating.

[0090] A region on an upper side of the shaft 71 is inside the shaft
supporter body 75. Meanwhile, a key 115 is provided at an upper part of
the shaft 71. As this key 115 is engaged with a key groove 117 provided
in the shaft supporter body 75, the shaft 71 is prevented from rotating
relative to the shaft supporter body 75 but is rendered movable in the
vertical direction relative to the shaft supporter body 75.

[0091] A lower end of the shaft supporter body 75 is supported so as to be
rotatable relative to the gauge nut 57 through a bearing such as a thrust
bearing 120. Here, when a downward force is applied to the pressing body
81 in the state shown in FIG. 8, the force thus applied is transmitted to
the gauge nut 57 via a bearing 119, the lower-side pressing-body
supporter body 77, the shaft supporter body 75, and the bearing 120,
thereby contracting the lifer spring 65 and allowing the gauge nut 57
(the shaft 71) to move downward.

[0092] The lower side of the shaft supporter body 75 is inside the inner
holder 83 and the shaft supporter body 75 can move vertically relative to
the inner holder 83. Meanwhile, the key 115 provided at the upper part of
the shaft 71 is also engageable with a key groove 121 that is provided in
an inner circumference of the inner holder 83.

[0093] Specifically, in the state shown in FIG. 8, the key 115 provided at
the upper part of the shaft 71 is located above the key groove 121 in the
inner holder 83 and therefore separated from this key groove 121.
However, when a downward force is applied to the pressing body 81 in the
state shown in FIG. 8, the shaft supporter body 75 and the shaft 71
descend relative to the inner holder 83. Accordingly, the key 115
provided at the upper part of the shaft 71 is engaged with the key groove
121 in the inner holder 83, and the key groove 111 at the lower part of
the shaft 71 is separated from the key 113 on the outer holder 55. Hence,
the shaft 71 (the shaft supper body 75 and the tap 43) is allowed to
rotate by way of rotation of the inner holder 83 (the driving block 85).
Moreover, since the master screws 41 and 45 are threadedly engaged with
each other, the shaft 71 (the tap 43) is allowed to descend by way of
rotation of the shaft 71.

[0094] The lower-side pressing-body supporter body 77 is integrally
provided on an upper end of the shaft supporter body 75. The pressing
body 81 is rotatably provided above the lower-side pressing-body
supporter body 77 via the bearing such as the thrust bearing 119
mentioned previously. Meanwhile, the ring-like upper-side pressing-body
supporter body 79 is integrally provided in the vicinity of an upper part
of the lower-side pressing-body supporter body 77. The pressing body 81
is pressed by this upper-side pressing-body supporter body 79 and is
thereby prevented from being separated upward from the lower-side
pressing-body supporter body 77.

[0095] Here, outside diameters of the pressing-body supporter bodies 77
and 79 are set slightly smaller than an inside diameter of the ring gear
29 and an inside diameter of the through-hole 21A of the gear holder 31.
Moreover, by pressing the tapping tool 25 downward by use of the striker
15 in the state of being disposed on the mounting section 33 of the upper
turret 9 and the adapter 21 for tapping, the pressing-body supporter
bodies 77 and 79 as well as the pressing body 81 are allowed to enter the
inside of the ring gear 29 and of the through-hole 21A on the gear holder
31.

[0096] Meanwhile, outside diameters of the driving block 85 and the outer
holder 55 are set slightly smaller than an inside diameter of the
through-hole of the mounting section 33 of the upper turret 9, the inside
diameter of the ring gear 29, and the inside diameter of the through-hole
21A of the gear holder 31 so that the tapping tool 25 can be inserted to
and disposed in the mounting section 33 of the upper turret 9 and the
adapter 21 for tapping.

[0097] A key (a pin) 123 is provided to and protrudes from the outer
circumference of the driving block 85. When this key 123 enters a key
groove 125 formed in an inner circumference of the ring gear 29 and gets
engaged therewith (see FIG. 11), the driving block 85 is allowed to
rotate along with rotation of the ring gear 29.

[0098] Note that a groove 127 for the key 123 on the driving block 85 to
enter is also foamed inside the through-hole 21A of the gear holder 31.
The key 123 on the driving block 85 of the tapping tool 25 located on the
left side in FIG. 11 is engaged with the groove 127 provided in the
through-hole 21A of the gear holder 31. Accordingly, the driving block 85
does not rotate along with rotation of the ring gear 29 on the left side
in FIG. 11. However, by pressing the pressing body 81 downward, the
driving block 85 on the left side in FIG. 11 moves downward and is
engaged with the key groove 125 in the ring gear 29 so as to allow the
driving block 85 to rotate along with rotation of the ring gear 29.

[0099] In the tapping tool 25 shown on the right side in FIG. 11, the key
123 on the driving block 85 is engaged with the key groove 125 formed
inside the ring gear 29. Accordingly, the driving block 85 is allowed to
rotate along with rotation of the ring gear 29 even in the state shown in
FIG. 11. Further, in the tapping tool 25 shown on the right side in FIG.
11, the key 123 on the driving block 85 remains engaged with the key
groove 125 in the ring gear 29 even when the pressing body 81 is pressed
downward and the driving gear 85 moves downward.

[0100] Moreover, when the pressing body 81 is pressed downward in the
state shown in FIG. 11, the shaft supporter body 75 and the shaft 71 also
move downward, whereby the key groove 111 at the lower part of the shaft
71 is disengaged from the key 113 on the outer holder 55 and the key 115
provided at the upper part of the shaft 71 is engaged with the key groove
121 in the inner holder 83. Hence a rotative force of the ring gear 29
(the driving block 85 and the inner holder 83) is transmitted to the
shaft 71 (the tap 43) so that the shaft 71 can move downward while
rotating.

[0101] Now, the adapter 21 for tapping will be described further.

[0102] Among the four ring gears 29, the tooth portions of a pair of ring
gears 29 on a diagonal line (the ring gear 29A on the lower left side
shown in FIG. 10 and the ring gear 29C on the upper right side shown in
FIG. 10) are located higher like the ring gear 29A shown on the right
side in FIG. 11. Meanwhile, among the four ring gears 29, the tooth
portions of a pair of ring gears 29 on the other diagonal line (the ring
gear 29B on the upper left side shown in FIG. 10 and the ring gear 29D on
the lower right side shown in FIG. 10) are located lower like the ring
gear 29D shown on the left side in FIG. 11. Meanwhile, in the plan view,
the intermediate gear 35 is located inward of the four ring gears 29 as
shown in FIG. 10.

[0103] Moreover, an adapter 23 for tapping-unit rotational drive is
provided above the upper turret 9 and in the vicinity of the inside of
the adapter 21 for tapping (the inside of the upper turret 9 in the
circumferential direction). The adapter 23 for tapping-unit rotational
drive is provided with multiple (two, for example) rotation input shafts
129 (129A and 129B) and these two rotation input shafts 129 are
interlocked and connected with an output gear 133 via a gear train 131.
Moreover, the output gear 133 is rotated by inputting a rotative force
from an actuator (not shown) provided in the turret punch press 1 to one
input shaft out of the two input shafts 129. As shown in FIG. 10, the
output gear 133 is meshed with the ring gear 29C out of the four ring
gears 29.

[0104] In this way, when a rotative force is inputted to the rotation
input shaft 129, the ring gears 29 rotate in the same direction at the
same turning angle velocity.

[0105] Meanwhile, the outer holder 55, the driving block 85, the release
lever 91, the key 123, and the pressing-body supporter bodies 77 and 79
are made of insulators that block electricity, or alternatively, surfaces
of the outer holder 55, the driving block 85, the release lever 91, the
key 123, and the pressing-body supporter bodies 77 and 79 are covered
with insulative coatings. Hence, the rotating body 39 (the tap 43) is
electrically insulated from the adapter 21 for tapping and the mounting
sections 33 of the upper turret 9 when the tapping tools 25 are disposed
in the through-holes of the gear holder 31, the through-holes of the ring
gears 29, and the mounting sections 33 of the upper turret 9.

[0106] Next, operations of the turret punch press 1 will be described by
referring to FIG. 11 to FIG. 14(b).

[0107] First, as shown in FIG. 11, as an initial state, the upper turret
9, the striker 15, and the workpiece W subjected to a pilot hole process
are located at predetermined positions. Here, it is assumed that the
rotating bodies 39 of the tapping tools 25 are located at the ascending
ends and no rotative force is inputted to the adapter 23 for tapping-unit
rotational drive.

[0108] In the initial state, when the striker 15 of the turret punch press
1 descends under control of an unillustrated control device and presses
down the rotating body 39 of the tapping tool 25 shown on the right side
in FIG. 12, the lifter springs 59 and 65 are contracted, and the rotating
body 39 of the tapping tool 25 on the right side descends as a
consequence.

[0109] Subsequently, when the rotating body 39 is rotated by way of the
adapter 23 for tapping-unit rotational drive, the lifer spring 65 is
contracted and the tap 43 performs tapping on the workpiece W as shown on
the right side in FIG. 13.

[0110] Thereafter, the rotating body 39 is inversely rotated by way of the
adapter 23 for tapping-unit rotational drive to establishing the state
shown in FIG. 12, and the workpiece W is moved and positioned to perform
subsequent tapping. The subsequent tapping is carried out after this
moving and positioning procedure.

[0111] The above-described operations are shown in a timechart in FIG.
14(a).

[0113] Note that it is also possible to inversely rotate the rotating body
39 after performing one tapping to establish the state shown in FIG. 12,
then to move the striker 15 of the turret punch press 1 upward to
establish the state shown in FIG. 11, and thereafter to perform the
subsequent tapping (see FIG. 14(b)).

[0114] The above-mentioned description of the operations exemplifies the
case of performing tapping by using the tapping tool that is disposed in
the ring gear 29A out of the four tapping tools. However, it is also
possible to perform tapping on the workpiece W by using a different
tapping tool 25 such as the tapping tool disposed in the ring gear 29D.

[0115] According to the turret punch press 1, it is possible to dispose
the tapping tools 25 on the upper turret 9 and use the tapping tools 25
by disposing, on the upper turret 9, the adapter 21 for tapping that is
mountable on the upper turret 9. Meanwhile, if the adapter 21 for tapping
is detached from the upper turret 9, then it is possible to dispose
punching tools on the upper turret 9 and use the punching tools. Hence,
it is possible to handle various processes easily by using the single
turret punch press 1.

[0116] Moreover, according to the adapter 21 for tapping, there are the
regions where the ring gears 29 overlap one another. These overlapping
regions enable the downsizing of the adapter 21 for tapping and thereby
space saving can be achieved.

[0117] Incidentally, the adapter 21 for tapping is usable not only as the
adapter dedicated for the tapping tools but also as the adapter for the
punching tools.

[0118] Specifically, it is possible to handle various processes by
detaching the adapter 21 for tapping and directly disposing the punching
tools on the upper turret 9 as described above; instead of this, it is
also possible to insert and dispose the punching tools into the adapter
21 for tapping in lieu of the tapping tools 25 without detaching the
adapter 21 for tapping.

[0119] In this case (when the punching tools are inserted and disposed
into this adapter 21 for tapping in lieu of the tapping tools 25), a
rotative force is not transmitted to any of the punching tools by
rotating the ring gears 29 because the punching tools are not provided
with the pins 123 to be engaged with the key grooves 125 formed in the
inner circumference of the ring gears 29. Hence, the punching tools can
perform punching at predetermined angles and in predetermined tool shapes
without being rotated.

[0120] Meanwhile, it is also possible to use the adapter 21 for tapping as
the adapter for both of tapping and punching by inserting the tapping
tools into two of the four stations of the adapter 21 for tapping and
inserting the punching tools into the other two stations on the adapter
21 for tapping, so as to be able to handle various processes.
Specifically, it is possible to dispose the tapping tools in some
stations of the multiple stations on the adapter 21 for tapping and to
insert the punching tools to some other stations thereof.

[0121] Meanwhile, since the rotating body 39 of the tapping tool 25 does
not rotate in the state where the tapping tool 25 is taken out of the
upper turret 9, it is not necessary to align a turning angle (a phase) of
the rotating body 39 relative to the cylindrical body 37 of the tapping
tool 25 when disposing the tapping tool 25 on the upper turret 9. Hence,
it is possible to dispose the tapping tool 25 on the upper turret 9
easily.

[0122] Meanwhile, when the tapping tool 25 is mounted on the upper turret
9, the rotating body 39 of the tapping tool 25 and the tap 43 disposed on
this rotating body 39 are electrically insulated from the upper turret 9.
Accordingly, when performing, for example, tapping on the workpiece W, it
is possible to detect contact of the tap 43 with the workpiece W by use
of a touch sensor.

[0123] Next, a tap die based on the present invention which is used in
cooperation with the tapping tool described in the above embodiment will
is be described by using the drawings.

[0124] First, referring to FIG. 15 to FIG. 18(b), as similar to a general
tap die, a tap die 301 according to the embodiment of the present
invention includes a cylindrical die body 303 to be mounted in a
detachably replaceable manner on a die holder (not shown) in the punch
press. Moreover, an inner cylinder 307, which includes a tap contact
member 305 to be pressed downward by the tap 43 being rotatably and
vertically movably provided to the tap tool 25 (see FIG. 11), is located
inside this tap body 3 so as to be vertically movable and to be biased
upward.

[0125] To be more precise, the die body 303 is mounted in a detachably
replaceable manner into a die mounting hole (not shown) provided to the
die holder while retaining a tiny gap therebetween. A circumferential
groove 309 corresponding to a communication port (not shown) that is open
so as to communicate with the die mounting hole is formed in an outer
circumferential surface of this die body 303. Moreover, an air supply
port 311 communicating with the circumferential groove 309 and
penetrating inward through the die body 303 are formed in multiple
positions on the die body 303. The communication port (not shown) is
connected to an air source (not shown) through a connecting path (not
shown) and this connecting path is provided with a flow switch (not
shown) representing an example of a fluid sensor for detecting presence
and absence of an air flow.

[0126] The flow switch performs an ON operation when a large amount of air
is flowing through the connecting path and performs an OFF operation when
a large amount of air is not flowing through the connecting path. Note
that the flow switch is so provided as not to perform the ON operation by
presence of a small amount of an air flow that flows out of the tiny gap
between the die mounting hole and the die body 3. Therefore, it is
possible to detect whether or not a large amount of air is flowing
through the connecting path, on the basis of the ON operation and the OFF
operation of the flow switch. Note that the flow switch may be one with a
publicly-known configuration and detailed description of the
configuration of the flow switch will be omitted herein.

[0127] The inner cylinder 307 being vertically movably provided inside the
die body 303 is so formed that its outside diameter is nearly equal to
inside diameters of the die body 303 and a hold ring 315, which is
detachably attached to an upper part of the die body 303 by use of
fixtures 313 such as bolts, in order to prevent chips from coming into
(entering) the gap between the die body 303 and the inner cylinder 307.
Specifically, clearances among the die body 303, the hold ring 315, and
the inner cylinder 307 are formed into tiny clearances so as to avoid
entrance of chips. Moreover, an upper end (an upper surface) 307U of the
inner cylinder 307 nearly coincides with an upper end (an upper surface)
315U of the hold ring 315 in a normal state.

[0128] In order to bias the inner cylinder 307 always upward relative to
the die body 303, an elastic member 319 such for example as a coil spring
(see FIG. 18(b)) is elastically set between anti-rotation keys 317
provided in multiple positions on the inner cylinder 307 and a bottom
part of the die body 303. Moreover, the anti-rotation keys 317 come into
contact with a lower surface of the hold ring 315 to block detachment
upward.

[0129] The tap contact member 305 is formed of a plate material which is
elongated in an orthogonal direction to a shaft center of the inner
cylinder 307 (a radial direction) and is attached to an upper end side of
the inner cylinder 307. To be more precise, the tap contact member 305 is
in a state where its protrusions on both ends are engaged with an
engagement groove 321 formed radially in an upper part of the inner
cylinder 307. The tap contact member 305 detachably attachable by locking
screws 323 threadedly engaged with the inner cylinder 307 in the radial
direction.

[0130] An upper surface 305U of the tap contact member 305 is provided at
a lower position than the upper end 307U of the inner cylinder 307.
Moreover, the upper surface 305U is formed into a curved surface whose
both ends in the thickness direction of the tap contact member 305 are
lower so that the chips can fall easily. Further, a width dimension of
the tap contact member 305 in the vertical direction is set greater than
the thickness dimension thereof in order to prevent chips from twining.
To be more precise, the width dimension of the tap contact member 305 in
the vertical direction is set to be several times to about dozen times as
large as the thickness dimension thereof in order to prevent chips, which
are generated in a long helical shape as a result of tapping with the tap
provided to the tap tool, from twining or tangling.

[0131] Upper and lower communicating portions 325A and 325B
communicatively connectable to and disconnectable from the air supply
ports 311 provided to the die body 303 are provided in an outer
circumferential surface of the inner cylinder 307. To be more precise,
the communicating portions 325A and 325B are formed in the following
manner: a concave portion 325 elongated in the vertical direction is
formed in the outer circumferential surface of the inner cylinder 307 in
regions corresponding to the air supply ports 311; and a tong-shaped land
portion 325C serving as a convex portion is provided at an intermediate
portion, in the vertical direction, of the concave portion 325 to thereby
partition a portion located on one side of the concave portion 325 into
the communicating portion 325A and the communicating portion 325B.
Moreover, air ejection holes 327 (see FIG. 18(a)) directed downward are
provided in an inner circumferential surface of the inner cylinder 7 so
as to communicate with the concave portions 325.

[0132] According to this configuration, even in the configuration to
partition the communicating portions 325A and 325B vertically, the air
ejection port 327 is common due to the configuration in which the
communicating portions 325A and 325B are provided to the one-side
portions of the concave portion 325. Hence, it is possible to simplify
the configuration.

[0133] In the above-described configuration, in the state where the tap
die 301 is mounted into the die mounting hole of the die holder provided
to the punch press, the inner cylinder 307 is in the state of being
lifted to the uppermost position by the biasing force of the elastic
member 319 as shown in FIG. 17(a) to FIG. 18(b). The upper end (the upper
surface) 307U of the inner cylinder 307 is in the state of nearly
coinciding with the upper end of the die body 303, i.e., the upper end
(the upper surface) 315U of the hold ring 315. Moreover, the air supply
ports 311 provided to the die body 3 are in the state of communicating
with the communicating portions 325B on the lower side of the concave
portions 325 formed in the outer circumferential surface of the inner
cylinder 307 as shown in FIGS. 17(a) and 17(b).

[0134] Accordingly, the air supplied from the air source is directed and
ejected from the air ejection holes 327 provided to the inner cylinder
307 in the downward direction into the inner cylinder 307, thereby
causing an action to suction the air from the upper part of the inner
cylinder 307 into the inner cylinder 307. Meanwhile, the flow switch
serving as the fluid sensor provided to the connecting path connected to
the air source is in the ON-operation state.

[0135] A pilot hole in the workpiece is positioned above the tap die 301
when the inner cylinder 307 is in the state of being lifted to the
uppermost position as described above. Then, the tap tool is moved down
to a predetermined height position by use of the ram (the striker)
provided to the punch press in order to perform tapping on this pilot
hole. After the workpiece is pressed and fixed to the upper surface of
the hold ring 315 on the tap die 301 by using this tap tool or while
maintaining the tap tool in a state of being slightly separated from the
workpiece, the tap provided to the tap tool is rotated and moved
downward. As a result, the tapping is performed on the pilot hole in the
workpiece with the tap as similar to a conventional typical tap tool.

[0136] In performing the tapping on the pilot hole in the workpiece as
described above, as a lower end of the tap 43 comes into contact with the
tap contact member 305, the inner cylinder 307 is moved down gradually
against the biasing force of the elastic member 319 as shown in FIGS.
19(b) and 19(c) (note that illustration of the workpiece is omitted in
FIG. 19(a) to FIG. 20(b)). Then, the state of communication between the
lower communicating portion 325B formed in the outer circumferential
surface of the inner cylinder 307 and the air supply port 311 provided to
the die body 303 is gradually interrupted. That is, the communication is
blocked when the air supply port 311 faces the land portion 325C.

[0137] As described above, when the air supply port 311 provided to the
die body 303 is in the state of facing the land portion 325C of the inner
cylinder 307 and there is built a state where the communication is
blocked because of the air supply portion 311 facing the land portion
325C, the ram provided vertically movably to the punch press is in the
state of descending to a predetermined descending position, while the tap
provided to the tapping tool is in the state of being rotated by a preset
number of revolutions and descending from a predetermined height position
by a prescribed stroke length in light of a relation between the number
of revolutions and the pitch of the tap. Specifically, this is the moment
when the tap 43 and the inner cylinder 307 descend to the lowest
positions by the prescribed stroke length. After the tap 43 descends to
the lowest position as described above, the tap 43 is inversely rotated
and the ram is lifted up, thereby completing the tapping on the pilot
hole in the workpiece.

[0138] Therefore, if the flow switch serving as the fluid sensor performs
ON-OFF-ON operations when the tap 43 is changed from positive rotation to
negative rotation to be lifted up from the lowest descending position, it
is possible to detect that the tapping is normally performed. Here, when
the flow switch does not shift to the OFF state but continues the ON
state even if the tap 43 is allowed to descend along with positive
rotation, then it is possible to detect that the tap has not come into
contact with the tap contact member 305. Through such detection, it is
possible to detect that the tap is broken, that the tap tool is not
provided with the tap, or that the tap is shorter than the prescribed
length.

[0139] Meanwhile, at the time of operations in which the flow switch shows
the ON, OFF, and OFF states when the tap 43 operates with positive
rotation and negative rotation, it is possible to detect that the tap is
in a descending state. Specifically, in this case, it is possible to
detect that the tap is maintaining its position without being detached
upward from the workpiece.

[0140] Further, at the time of operations in which the flow switch shows
the OFF, OFF, and OFF states when the tap 43 operates with positive
rotation and negative rotation, it is possible to detect that the inner
cylinder 307 has already reached the descending state and is in a state
of a sliding failure.

[0141] Moreover, if the state of the flow switch is changed as ON, OFF,
and ON when the tap 43 descends along with positive rotation, it is
possible to detect that the tap provided to the tap tool is the tap
having a larger diameter than that of a prescribed tap, or that the
length of the tap is longer than the prescribed length. Specifically, if
the tap 43 descends from the state shown in FIG. 19(a) to press down the
tap contact member 305, the air supply ports 311 provided to the die body
303 are in the blocked state by the land portion 325C of the inner
cylinder 307, and the flow switch is in the OFF operation state in cases
of the states of FIG. 19(c) and FIG. 20(a). If the tap 43 further
descends from this state to the lowest descending position, the inner
cylinder 307 descends further by the tap 43. The upper communication
portion 325A in the concave portion 325 formed in the outer
circumferential surface of the inner cylinder 307 communicates with the
air supply port 311 provided to the die body 303, whereby the flow switch
is set to the ON state.

[0142] Therefore, if the flow switch performs the ON, OFF, and ON
operations at the time of descending action of the tap, it is possible to
detect such operations as overstroke of the tap. Accordingly, in this
case, it is appropriate to replace the tap tool with another tap tool
provided with the prescribed tap or to replace the tap with another tap
having the prescribed length.

[0143] As described previously, chips generated by performing tapping on
the pilot hole in the workpiece fall into the inner cylinder 307. In this
case, some of the chips tend to remain on the upper surface 305U of the
tap contact member 305. However, since the upper surface 305U is formed
into the curved surface whose both ends in the thickness direction of the
tap contact member 305 are lower. Accordingly, the chips fall without
remaining on the upper surface 305U. Meanwhile, chips having relatively
long helical shapes tend to twine and tangle around the tap contact
member 305. However, since the width dimension of the tap contact member
305 in the vertical direction is fanned into a width dimension large
enough to avoid the chips from twining and tangling. Hence, it is
possible to prevent the chips from twining and tangling around the tap
contact member 305.

[0144] Furthermore, the inner cylinder 307 is so formed that its outside
diameter is nearly equal to the inside diameter of the tap body 303.
Moreover, in the normal state, the upper end (the upper surface) 307U of
the inner cylinder 307 is retained in the state of nearly coinciding with
the upper end of the tap body, i.e., the upper end (the upper surface)
315U of the hold ring 315. Therefore, it is possible to perform vertical
movement of the inner cylinder 307 relative to the tap body 303 always
smoothly while preventing chips from entering the gap between the tap
body 303 and the inner cylinder 307.

[0145] As it is understood from the description given above, the tap die
301 according to this embodiment improves a discharge performance of
chips generated at the time of tapping, whereby smooth vertical movement
of the inner cylinder 307 relative to the die body 303 will not be
disturbed. Moreover, it is possible to detect the state of air supply
into the inner cylinder 307 of the tap die 301 with the fluid sensor, and
to cause the fluid sensor to perform the ON, OFF, and ON operations when
the inner cylinder 307 descends by way of the tap of the punch press.
Hence, it is possible to detect overstoke of the tap easily.

[0146] Moreover, since the fluid sensor is formed of the flow switch that
detects the air flow inside the connecting path, it is possible to detect
the air flow accurately without being affected by pressure fluctuation
unlike a pressure switch. Hence it is possible to accurately detect
communicative connection to or disconnection from the air supply ports
311 provided to the die body 303.